I don't know that much about vertual models, however you said your working with a green screen so if your interested in some background news style studio loops, logos, countdowns and other animated video loops you can find some free ones here. http://thecliparchive.com/clip_archivemovietools.php, I have played around with a few for my News Spoofs and they loop seemlessly. I thought they are pretty cool, especially the rotating globes, you can overlay your own logo on top of them. I hope they help you.
Ryan AKA rgander1 AKA "the videobloggoligist"